[Asterisk-Users] Asterisk VIA SSH Tunnels

[steve at daviesfam.org]

On Thu, 14 Oct 2004, Brian Capouch wrote:

> steve at daviesfam.org wrote:
> > 
> > On Wed, 13 Oct 2004, Chris Travers wrote:
> > 
> > 
> >>What happens then is that a dropped packet will not cause "jitter" but 
> >>rather a delay in the audio.  This is the problem.
> > 
> > 
> > A delay in the audio IS jitter.
> > 
> 
> Actually isn't it rather that a *variation* in delay from sample to 
> sample is jitter?
> 
> I can put up with a lot of delay as long as its consistent.
> 
> I'll gladly stand corrected. . . .

No need for you to be corrected.  Jitter is indeed variation in delay.

But tunnelling iax or rtp through a tcp-based tunnel will exactly result
in variable delay.  When a packet on the tcp level is lost, tcp will
retransmit it.  In the meantime - whilst the missing packet is detected
and recovered, all the packet flow stops for 2xround-trip+slow-start so
the receiver sees a spike in delay, ie jitter.

Steve